This is a Phase 3, randomized, parallel-group, multicenter, double-dummy, double-blind study with a screening period. Subjects will receive one of the following three treatment groups for 15 days: loratadine 10 mg/montelukast 10 mg combination, pseudoephedrine 240 mg, or placebo. The primary objective of this study is to assess the efficacy of the combination of loratadine/montelukast, a once-daily tablet containing 10 mg loratadine and 10 mg montelukast, compared with placebo in subjects with seasonal allergic rhinitis (SAR) in relieving the symptom of nasal congestion. The safety profile of combined loratadine/montelukast relative to placebo and pseudoephedrine will also be evaluated.